Luminaire



Oct. 5, I943. T. w. ROLPH LUMINAIRE Filed Sept. 25, 1,941

2 Sheets-Sheet 1 SPECl/L 19R INVENTOR 77mm): 111/904 PH BY 1 ATTORNEY Oct. 5, 1943.

T. w. ROL PH LUMINAIRE Filed Sept. 25, 1941 2 Sheets-Sheet 2 INVENTOR Eon/)5 h Aom/l ATTORNEY a (k -,5 1m; 2,330,924

- UNITED STATES PATENT OFFICE rmmmamn Thomas'W. Rolph, Newark. Ohio, assignor to Holophane Company, Inc., New York, N. Y., a

'corporation of Delaware Application September 25, 1941, Serial No. 412,209

' V 3'Clahns. (Cl. 240-25) and diameter. Thisis typically in the form of The present invention relates to luminaires,

and ismore particularly directed toward luminaires designed for street and highway lighting, and employinghorizontal lamps such as sodium lamps or mercury lamps.

The present invention contemplates luminaires for the above purpose wherein the laterally emitted light from a horizontal sodium lamp is intercepted by the side walls of an inverted specular trough and reflected downwardly across the axis of the trough at angles which are steeper than the angles customarily employed in street and highway lighting, and this relatively steep downwardly emitted light is intercepted by the downwardly converging sides of a retracting trough having prisms arranged to elevate the light to angles above the nadir suitable for street and highway lighting and to deviate the light laterally so that the emitted beams are not opposite one another. With this arrangement the luminaires may be mounted a sodium lamp and flask.

As shown in Figures 1 to 5, inclusive, the

- source is received in an inverted reflecting above the surface to be illuminated and to one side of the road or street, and the dominant light rays directed toward the center of the street or road.

The sodium lamp is a source of substantial diameter and a further object of the invention is to make the prismatic refractor of suflicient depth to intercept the lowermost reflected rays originating in the upper part of this lamp.

The annexed drawings and the following description set forth in detail certain apparatus embodying the invention, such disclosed apparatus constituting, however, but three of the various forms in which the principle of the invention may be used.

In these drawings:

Figure 1 is a diagrammatic vertical cross section through the luminaire illustrating the direction of light rays relative to the vertical;

Figure 2 is a top plan view of the luminaire showing the horizontal direction of the light rays;

Figure 3 is a vertical sectional view through one form ofconstruction;

Figure 4 is a side elevational view of one of the prismatic plates shown in Figure 3;

Figure -5 is a diagrammatic perspective view of the luminaire of Figure 3; and

Figures 6 and '7 are cross sectional views similar to Figure 3 showing modified forms of construction. I

As shown in the drawings the luminaire has a horizontal light source ID of substantial length trough ll which extends a substantial distance below the horizontal plane through the light source. The angle from the center of the light source to the lower edge of the reflector ranges from about in Figure 1 to in Figures 6 and '1 as indicated in the drawings. The bottom of the reflecting trough is closed by twoprismatic plates I2, I2 which meet in the vertical plane below the center of the light source so that the unit is symmetrical on opposite sides of this vertical plane. The drawings omit the mechanical details of the structures employed for securing the reflecting plates to ether and supporting them from the reflector.

The line [5 extending-from the center of the source to the upper'prism of the retracting plate is at an angle of approximately 55 with the nadir so that the reflector and refractor supports screen off all light above this line l5. The reflecting trough is specular and the side walls are parabolic cylinders with the focus of each parabola at the light source and its axis extending downwardly, substantially parallel with the line l5. The upper part of the reflector is shaped to reflect light generally downward. Light rays I1 and I8 originating at the center of the light source are reflected obliquely downward, as indicated at 19 and 20, in directions substantially parallel with the out ofl! line l5. Owing to the size of the light source a substantial amount of light comes from points spaced the median plane of the luminaire and are wide enough to intercept the lowermost specularly reflected ray 22 as indicated. The prismatic panels [2, II are provided with retracting prisms 23 which extend obliquely oi the plates as will'appear more clearly in Figures 4 and 5, and receive the downwardly-sloping light rays I9, 20 having an angle of approximately 55 with the nadir. v

These prisms are calculated to have the proper general slope as well as surfaces of the proper angle to accept these rays and elevate them so that they have an angle of approximately with the nadir and a horizontal angle somewhat less than 90 with the median plane. The emitted rays are indicated at 25 in Figures 1, 2 and 3 and these angles are shown in Figures 1 and 3.

Thus one set oi! oblique prisms accomplishes both vertical and lateral redirection and the outside of the plates may be smooth instead of uneven as would be the case were crossed prisms used.

The lumniaire will therefore produce two beams of light wherein the dominant rays are at angles of about 75 with the nadir and are somewhat out of 180 in horizontalplanes. Owing to the size 01 the source there will, of course, be considerable spread of the light rays in vertical planes and owing to its length there will be considerable spread in horizontal planes. Direct light rays such as 26 will be deviated in vertical planes so as to be spread away from the nadir, as indicated at 21, but, of course, will not be elevated as high as the reflected light. The lateral deviation will, however, be comparable.

Where the mounting height and spacing of the unit is such as to require a beam slope other than 75, the lamp may be elevated or lowered from the position indicated.

In the arrangement shown in Figure 6 the light source I is received in a reflecting trough 30 with a screening angle of approximately 65.

\ Its side walls are parabolic and reflect the light obliquely downwardly as indicated at 3|. The

lowermost reflected rays are indicated at 32 and it will be obvious from the drawings that the specularly reflected light at angles below the cut off line 33 will be acted upon by the plates 34, 34 in the same way as above described. In the construction here shown the reflecting trough is made much shallower than in Figure 3, and its upper wall 35 is provided with a white difiusing finish.

In the arrangement shown in Figure '7 the parabolic reflectors 40, 40 of screening angle of substantially 65 terminate below an upper reflector 4| so as to provide the ventilating space The prismatic closure has two retracting plates 43, 43 similar to the plates above described, and a central fluted, light diffusing plate 44. Inthis form of construction the plates 43, 43 are steeper than the plates I2 and 34 and light below the specularly reflected ray 45', corresponding to the ray 45 originating at the center of the source, is allowed to fall on the bottom plate 44.

While I have 'shown three specific constructions for the, embodiment of the invention, it should be understood the same is only for the purpose of illustrating preferred embodiments thereof. Changes in the details may be made without departing from the scope of the invention and I do not wish to be understood as limiting myself except as such limitations may appear in the hereinafter contained claims.

What is claimed is:

1. Meansiior producing from a horizontal cylindrical light source of extended length two beams of parallel light rays directed downwardly at angles of substantially above the nadir and having between them a horizontal angle of substantially less than comprising an inverted reflecting trough which screens off all light down to angles substantially 10 to 20 less than said beam angle above the nadir and having sides oi parabolic contour in vertical section which specularly reflect the intercepted light out of its mouth and across the axial plane thereof at angles substantially parallel with said angle of reflector cut-off, and two prismatic retractors extending downwardly and inwardly from the lower edges of the reflector, each of a depth to receive the light reflected by the other side of the reflector after crossing the axis, and having obliquely disposed parallel light retracting prisms which elevate the light so that it is transmitted at substantially 15 above nadir and deviate it horizontally so that the axes of the beams are substantially less than 180.

2. In a street lighting luminaire symmetrical on opposite sides of a vertical plane, a horizontal cylindrical light source of extended length in said vertical plane, an inverted reflecting trough having specularly reflecting side walls, and a prismatic light-retracting trough whose side walls converge inwardly from the lower edges of the reflector to said vertical plane, the upper edges of the side walls of the retracting trough being substantially below the source and providing a cut ofl angle for direct light in the order of 55 to 65 above the nadir, the profile of the sides of the reflecting trough being parabolic with coincident foci at the source and their axial planes of substantially the same slope as the angle of cut of! so that the specularly reflectedlight is directed obliquely downwardly and across the said vertical plane and generally parallel ,with the cut oil angle, the depth of the side walls 01 the refracting trough being suflicient to permit said reflected light to cross the said axis, the retracting trough walls comprising flat rectangular plates each having parallel obliquely extending retracting prisms which transmit the light at angles measured from the nadir which are higher than those of the reflected light. substantially 10 to 20 and deviate it horizontally so that the emitted beams are at less than 180 to one another.v

3. A luminaire such as claimed in claim 2, wherein the source is of substantial diameter'so that light rays originating in the upper part of the source are reflected downwardly at angles substantially below those originating at the axis of the source, and the retracting trough has additional depth to intercept said lower angle reflected light.

I THOMAS W. ROLPH. 

